Abstract: In order to prepare anti-fatigue peptides, pepsin was used to hydrolyze casein. Based on weight-loaded swimming time, the hydrolysis parameters substrate concentration, enzyme/substrate ratio, pH and temperature were optimized to obtain anti-fatigue peptides with the highest activity. Meanwhile, hydrolysates obtained under different hydrolysis conditions were analyzed by capillary electrophoresis. The optimal hydrolysis conditions were determined as 5 g/100 mL substrate, 1:30 of enzyme/substrate ratio, pH 2.5, and 43 ℃ of hydrolysis temperature. Mice were administrated with the hydrolysate obtained under these hydrolysis conditions at doses of 0.048, 0.24 g/(kg ·d) and 2.4 g/(kg ·d) for 28 d, and then subjected to weight-loaded swimming tests. The weight-loaded swimming time of mice administrated with the optimized hydrolysate was significantly prolonged when compared to the same doses of hydrolysates obtained under non-optimal conditions. The optimized hydrolysate and other hydrolysates displayed significant differences in their capillary electrophoresis patterns: the maximum peak appearance time of the optimized hydrolysate was different from that of other hydrolysates and it had a unique peak at 17-18 min.

Key words: casein, anti-fatigue peptide, weight-loaded swimming, capillary electrophoresis